CN117491905A - DC system ground fault real-time monitoring system and control method thereof - Google Patents
DC system ground fault real-time monitoring system and control method thereof Download PDFInfo
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- CN117491905A CN117491905A CN202311538692.0A CN202311538692A CN117491905A CN 117491905 A CN117491905 A CN 117491905A CN 202311538692 A CN202311538692 A CN 202311538692A CN 117491905 A CN117491905 A CN 117491905A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
Abstract
The invention discloses a direct current system ground fault real-time monitoring system, which comprises a voltage detection device, a direct current transformer, a differential protection device, a switch deflection acquisition module, an opening-in module, a DSP module, a CPU controller, a memory, an opening-out module, a communication module, a display device, a motor control module, a main switch for controlling opening and closing by a motor, a branch switch, a shunt switch, a bypass switch and a bypass switch; according to the real-time monitoring system for the grounding fault of the direct current system and the control method thereof, the zone where the grounding point is located can be rapidly positioned through the differential protection device, the motor is controlled to complete automatic switching on and off of the switch, the searching link of the grounding fault of the direct current system is automatically completed, the fault is automatically isolated after the fault point is found, and the bypass is adopted to recover power transmission; the fault can be rapidly positioned and found, the fault can be automatically isolated, the power supply requirement of the load of the fault line is recovered, and a standby power supply is not required to be added.
Description
Technical Field
The invention relates to the technical field of direct current system ground faults, in particular to a direct current system ground fault real-time monitoring system and a control method thereof.
Background
The direct current system provides a reliable direct current power supply for a control device, a signal device, a relay protection device, an automatic device, accident lighting and the like in a transformer substation. The system also provides a reliable operation power supply for operation, and the reliability of a direct current system plays a vital role in the safe operation of the transformer substation, thereby being the guarantee of the safe operation of the transformer substation. The main loads of the direct current system are a control loop and an electric protection device in electric equipment, various control cables in the equipment and cables related to other equipment are too many, and the situation that the direct current is grounded due to insulation damage of the cables is unavoidable. When the direct current system has two-point ground faults, the system ground short circuit can be formed, misoperation or refusal of a relay protection device, a signal and an automatic device can be caused, even the direct current safety is fused, the protection and automatic device and a control loop can thoroughly lose power, and the direct current system is interrupted and cannot work. When the direct current system has two-point ground faults, an maintainer cannot arrive at the site to process in time, adverse effects can be caused on the direct current system, serious faults of the direct current system can be developed, and huge threats are caused on insulation of the direct current system. The direct current system is damaged in insulation and cannot be replaced in time, so that the hidden danger of power failure is easily caused for important direct current loads. Thus, there is a need to properly and timely remove the ground loop from the system.
When the direct current in the prior art is grounded, the current is not obviously changed like the alternating current during grounding, so that an overcurrent protection mode is difficult to adopt, and if the ground current is simply relied on as a grounding criterion, the situation that the load is increased to cause the current to be increased and the system is misjudged to be grounded is easy to occur. If the leakage protection is adopted, the switch can be misoperation due to the fact that a cable line in the system is overlong and generates larger zero sequence current. Therefore, neither single overcurrent protection nor current leakage protection can be applied to a direct current system. At present, a direct current system has no technical measure for directly determining a grounding point, when direct current grounding occurs, most of direct current grounding is found by adopting a traditional path pulling method, each direct current branch is required to be opened and closed in an empty mode until faults disappear, the processing time is long, the steps are numerous, and the risk of misoperation is easy to occur. Therefore, a method for accurately positioning the grounding position without affecting the normal operation of the branch circuit is needed.
The application number is 201010229641.6 in the prior art, the patent name is a method and a device for automatically isolating and positioning the ground fault of a direct current system, and the application number is 201010594500.4, the patent name is a method for searching the direct current ground fault in an electric power system, and the method for adding a power supply is adopted to switch a direct current branch to a standby power supply, so that the input cost is increased and the maintenance cost is increased due to the addition of the standby power supply; and they can only be positioned on the whole main branch, and all branches and branches below the main branch still need to be switched all the way and all the way until the grounding point is found, and the accurate positioning of the specific grounding point can not be realized.
Disclosure of Invention
The invention aims to provide a direct current system ground fault real-time monitoring system and a control method thereof, when a direct current system has a ground fault, the direct current system ground fault real-time monitoring system can quickly position a grounding interval through a differential protection device according to the kirchhoff current law principle, the problem that current cannot be used as a direct current ground judgment basis is solved, and a specific grounding point is accurately positioned under the condition of ensuring no power loss through a bypass replacement method; and the direct current bypass is utilized to cut off the fault direct current circuit and cut off the direct current load to the bypass for supplying power.
The technical solution for realizing the purpose of the invention is as follows:
the direct current system ground fault real-time monitoring system is characterized by comprising a voltage detection device, a direct current transformer, a differential protection device, a switch deflection acquisition module, an opening module, a DSP module, a CPU controller, a memory, an opening module, a communication module, a display device, a motor control module, a main switch, a branch switch, a shunt switch, a bypass switch and a bypass switch, wherein the main switch is used for controlling opening and closing by a motor;
the output end of the voltage detection device is connected with the input end of the opening module, the voltage detection device transmits signals acquired in real time to the opening module, and the voltage detection device is used for detecting the voltage of the direct current bus in real time;
the output end of the direct current transformer is connected with the input end of the opening-in module, the direct current transformer transmits signals acquired in real time to the opening-in module, and the direct current transformer is used for acquiring currents flowing through the main switches, the branch switches and the shunt switches in real time;
the input end of the differential protection device is connected with the output end of the direct current transformer, the output end of the differential protection device is connected with the input end of the CPU controller, the differential protection device is used for monitoring differential current in the protection range in real time, and when detecting that the differential current is greater than the action fixed value of the differential protection device, the differential protection device sends an abnormal instruction to the CPU controller;
the output end of the switch deflection acquisition module is connected with the input end of the switch-in module, the switch deflection acquisition module changes a switch acquired in real time into a signal and transmits the signal to the switch-in module, and the switch deflection acquisition module is used for monitoring the switch to become information;
the input end of the switch deflection acquisition module is connected with the input end of the DSP module, and the switch deflection acquisition module is used for acquiring signals acquired by the voltage detection device, the direct current transformer and the switch deflection acquisition module in real time and transmitting the signals to the CPU controller through the DSP module;
the output end of the DSP module is connected with the input end of the CPU controller; the DSP module is used for converting the analog signals of the starting module into digital signals and transmitting the digital signals to the CPU controller;
the output end of the CPU controller is connected with the input end of the memory, and the CPU controller judges that the direct current system is in a normal or abnormal state currently through monitoring and analyzing signals, marks abnormal data and stores the abnormal data in the memory;
the input end of the opening module is connected with the output end of the CPU controller, and the output end of the opening module is connected with the input end of the communication module; the opening module is used for executing the command sent by the CPU controller and transmitting the command through the communication module;
the output end of the communication module is respectively connected with the input ends of the display device and the motor control module, and the communication module is used for receiving the signal transmitted by the opening module and displaying the alarm information on the display device;
the output end of the motor control module is respectively connected with the control ends of the main switch, the branch switch, the shunt switch, the bypass switch and the bypass switch, the motor control module receives the command transmitted by the communication module, and the motor control module realizes the switching of all the switches by controlling the forward and reverse rotation of the motor.
Preferably, the direct current bus is connected with a plurality of main switches, each main switch is connected with a plurality of branch switches, and each branch switch is connected with a plurality of branch switches; each branch switch is connected to the bypass switch through a bypass switch, and each branch switch is connected to the bypass switch through a bypass separator, and the bypass switch is connected with the direct current bus.
Preferably, the action constant value of the differential protection device is that the differential current percentage is greater than or equal to 20%, i.e. iiffect is greater than or equal to 20%, and the differential current percentage=the absolute value of the vector sum of all the branch currents/the absolute value of the total branch current is 100%.
Preferably, the intelligent mobile terminal also comprises a background control center and an intelligent mobile terminal, wherein the input end of the background control center is connected with the output end of the communication module, and the output end of the background control center is connected with the intelligent mobile terminal; the communication module transmits the signals to the background control center in a remote mode, and the background control center transmits the signals to the intelligent mobile terminal through wireless communication.
The control method of the direct current system ground fault real-time monitoring system is characterized by comprising the following steps of:
step one: when the voltage abrupt change U1 collected by the voltage monitoring device is less than 20 percent and the differential current I differential of the differential protection device is less than 20 percent, the voltage and the current are both normal interval values, the system control display device displays the normal running state of the system, and the system enters a normal running program;
step two: when the voltage abrupt change U1 collected by the voltage monitoring device is more than or equal to 20 percent and the differential current I differential of the differential protection device is less than 20 percent, the system detects that the voltage is obviously reduced, the system judges that the direct-current voltage is abnormal, the system controls the display device to send a direct-current voltage abnormality alarm, and the alarm information is uploaded to the background control center, so that the system enters a direct-current voltage abnormal operation program;
step three: when the voltage abrupt change U1 collected by the voltage monitoring device is less than 20 percent and the differential current I differential of the differential protection device is more than or equal to 20 percent, the system judges that the direct current is abnormal, the system controls the display device to send out a direct current abnormal alarm, and the alarm information is uploaded to the background control center, so that the system enters a direct current abnormal operation program;
step four: when the voltage abrupt change U1 collected by the voltage monitoring device is more than or equal to 20 percent and the differential current I differential of the differential protection device is more than or equal to 20 percent, the system judges that direct current grounding exists, the system controls the display device to send out a direct current grounding alarm, and the alarm information is uploaded to the background control center, so that the system enters a direct current grounding operation program; the system locates the protection range of the corresponding differential protection device and starts to search the fault line in the protection range; if the protection range of the system positioning differential protection device is a branch, executing a step five; if the protection range of the system positioning differential protection device is a shunt, executing the step six;
step five: according to a preset program of the system, namely according to preset numbers of branches 1 to n, firstly closing a bypass switch, then closing the bypass switch 1 according to the numbers, disconnecting the bypass switch 1, and the like, immediately stopping switching until the voltage is recovered to be normal, and judging that a grounding point exists in a branch k (k is less than or equal to n) switched for the last time; simultaneously, starting from k-1, switching the direct current branch which is already switched, firstly closing the corresponding branch switch k-1, separating the corresponding branch switch k-1, closing the corresponding branch switch k-2, separating the corresponding branch switch k-2, and the like, switching and recovering the original operation mode; at the moment, the grounding point of the branch k, namely, the space between the branch switch k and the branch direct current transformer k is isolated from a direct current system, and the non-grounding part is continuously supplied with power by a direct current bus through a bypass; the system sends out a direct current fault isolation and bypass starting alarm message;
step six: according to a preset program of the system, namely according to preset numbers of branches 1 to n, firstly closing a bypass switch, then closing the bypass switch 1 according to the numbers, disconnecting the bypass switch 1, and the like, immediately stopping switching until the voltage is recovered to be normal, and judging that a branch k (k is less than or equal to n) switched for the last time has a grounding point; simultaneously, starting the direct current shunt from k-1, which is already switched, firstly closing the corresponding shunt switch k-1, separating the corresponding side shunt switch k-1, closing the corresponding shunt switch k-2, separating the corresponding side shunt switch k-2, and the like, switching, and recovering the original operation mode; at the moment, the grounding point of the shunt k, namely, the shunt switch k and the shunt direct current transformer k are isolated from the direct current system, the non-grounding part is continuously supplied with power through the bypass by the direct current bus, and the system sends out direct current fault isolation and bypass starting alarm information.
Compared with the prior art, the invention has the remarkable advantages that:
(1) According to the real-time monitoring system for the grounding fault of the direct current system and the control method thereof, the zone where the grounding point is located can be rapidly located through the differential protection device, and only the line in the zone is required to be searched, so that the searching time is greatly shortened, and the rapid location of the grounding fault point is realized.
(2) The invention discloses a real-time monitoring system for the ground fault of a direct current system and a control method thereof, wherein the real-time monitoring system controls a motor to complete automatic switching on and switching off of a switch, automatically completes a searching link of the ground fault of the direct current system, automatically isolates the fault after finding out a fault point, and adopts a bypass to recover power transmission; the fault can be rapidly located and found, and the fault can be automatically isolated.
(3) The real-time monitoring system for the ground fault of the direct current system and the control method thereof provide a bypass loop, and the bypass is adopted to recover power transmission, so that the power supply requirement of the load carried by a fault line is recovered, and a standby power supply is not required to be increased.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a real-time monitoring system for ground faults of a dc system according to the present invention.
Fig. 2 is an electrical connection diagram of the real-time monitoring system for ground fault of the dc system according to the present invention.
Fig. 3 is a schematic diagram of the switch connection of the real-time monitoring system for ground fault of the dc system according to the present invention.
Fig. 4 is a schematic diagram of the connection of the differential protection device in the real-time monitoring system for the ground fault of the dc system according to the present invention.
Fig. 5 is a flow chart of a control method of the real-time monitoring system for the ground fault of the direct current system.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1:
1-3, a direct current system ground fault real-time monitoring system comprises a voltage detection device, a direct current transformer, a differential protection device, a switch deflection acquisition module, an opening-in module, a DSP module, a CPU controller, a memory, an opening-out module, a communication module, a display device, a motor control module, a main switch for controlling opening and closing by a motor, a branch switch, a shunt switch, a bypass switch and a bypass switch; the direct current bus is connected with a plurality of main switches, each main switch is connected with a plurality of branch switches, and each branch switch is connected with a plurality of branch switches; each branch switch is connected to the bypass switch through a bypass switch, and each branch switch is connected to the bypass switch through a bypass separator, and the bypass switch is connected with the direct current bus.
The output end of the voltage detection device is connected with the input end of the opening module, the voltage detection device transmits signals acquired in real time to the opening module, and the voltage detection device is used for detecting the voltage of the direct current bus in real time.
The output end of the direct current transformer is connected with the input end of the opening-in module, the direct current transformer transmits signals acquired in real time to the opening-in module, and the direct current transformer is used for acquiring currents flowing through the main switches, the branch switches and the shunt switches in real time.
The input end of the differential protection device is connected with the output end of the direct current transformer, the output end of the differential protection device is connected with the input end of the CPU controller, and the differential protection device is used for monitoring differential current in the protection range in real time; according to kirchhoff's current law, if the system has no grounding current, the corresponding current vector detected by the direct current transformer should be zero (the current is directed to the bus direction to be the positive direction), namely the sum of the current vectors measured by the differential protection device is zero, and if the direct current grounding occurs, the sum of the sampled current vectors of the direct current transformer is not zero, namely the sum of the current vectors measured by the differential protection device is not zero. When the differential current is detected to be larger than the action fixed value of the differential protection device, the differential protection device sends an abnormal instruction to the CPU controller; the action constant value of the differential protection device is that the differential current percentage is more than or equal to 20%, i.e. I differential is more than or equal to 20%, and the differential current percentage=the absolute value of the vector sum of all branch currents/the absolute value of the total branch current is 100%; i.e. I differential = |i1+i2+i3+i4+ia|/|ia| 100%, where I1, I2, I3, I4, iA are current vectors in fig. four.
The output end of the switch deflection acquisition module is connected with the input end of the switch-in module, the switch deflection acquisition module changes a switch acquired in real time into a signal and transmits the signal to the switch-in module, and the switch deflection acquisition module is used for monitoring the switch to become information;
the output end of the switching-in module is connected with the input end of the DSP module, and the switching-in module is used for receiving signals acquired by the voltage detection device, the direct current transformer and the switch deflection acquisition module in real time and transmitting the signals to the CPU controller through the DSP module.
The output end of the DSP module is connected with the input end of the CPU controller; the DSP module is used for converting the analog signals of the starting-in module into digital signals and transmitting the digital signals to the CPU controller.
The output end of the CPU controller is connected with the input end of the memory, and the CPU controller judges that the direct current system is in a normal or abnormal state currently through monitoring and analyzing signals, marks abnormal data and stores the abnormal data in the memory.
The input end of the opening module is connected with the output end of the CPU controller, and the output end of the opening module is connected with the input end of the communication module; the issuing module is used for executing the command sent by the CPU controller and transmitting the command through the communication module.
The output end of the communication module is respectively connected with the input ends of the display device and the motor control module, and the communication module is used for receiving signals transmitted by the opening module and displaying alarm information on the display device.
The output end of the motor control module is respectively connected with the control ends of the main switch, the branch switch, the shunt switch, the bypass switch and the bypass switch, the motor control module receives the command transmitted by the communication module, and the motor control module realizes the switching of all the switches by controlling the forward and reverse rotation of the motor.
The ground fault real-time monitoring system of the direct current system also comprises a background control center and an intelligent mobile terminal, wherein the input end of the background control center is connected with the output end of the communication module, and the output end of the background control center is connected with the intelligent mobile terminal; the communication module transmits the signals to the background control center in a remote mode, and the background control center transmits the signals to the intelligent mobile terminal through wireless communication.
As shown in fig. 5, a control method of a real-time monitoring system for ground faults of a direct current system includes the following steps:
step one: when the voltage abrupt change U1 collected by the voltage monitoring device is less than 20 percent and the differential current I differential of the differential protection device is less than 20 percent, the voltage and the current are both normal interval values, the system control display device displays the normal running state of the system, and the system enters a normal running program;
step two: when the voltage abrupt change U1 collected by the voltage monitoring device is more than or equal to 20 percent and the differential current I differential of the differential protection device is less than 20 percent, the system detects that the voltage is obviously reduced, the system judges that the direct-current voltage is abnormal, the system controls the display device to send a direct-current voltage abnormality alarm, and the alarm information is uploaded to the background control center, so that the system enters a direct-current voltage abnormal operation program;
step three: when the voltage abrupt change U1 collected by the voltage monitoring device is less than 20 percent and the differential current I differential of the differential protection device is more than or equal to 20 percent, the system judges that the direct current is abnormal, the system controls the display device to send out a direct current abnormal alarm, and the alarm information is uploaded to the background control center, so that the system enters a direct current abnormal operation program;
step four: when the voltage abrupt change U1 collected by the voltage monitoring device is more than or equal to 20 percent and the differential current I differential of the differential protection device is more than or equal to 20 percent, the system judges that direct current grounding exists, the system controls the display device to send out a direct current grounding alarm, and the alarm information is uploaded to the background control center, so that the system enters a direct current grounding operation program; the system locates the protection range of the corresponding differential protection device and starts to search the fault line in the protection range; if the protection range of the system positioning differential protection device is a branch, executing a step five; if the protection range of the system positioning differential protection device is a shunt, executing the step six;
step five: according to a preset program of the system, namely according to preset numbers of branches 1 to n, firstly closing a bypass switch, then closing the bypass switch 1 according to the numbers, disconnecting the bypass switch 1, and the like, immediately stopping switching until the voltage is recovered to be normal, and judging that a grounding point exists in a branch k (k is less than or equal to n) switched for the last time; simultaneously, starting from k-1, switching the direct current branch which is already switched, firstly closing the corresponding branch switch k-1, separating the corresponding branch switch k-1, closing the corresponding branch switch k-2, separating the corresponding branch switch k-2, and the like, switching and recovering the original operation mode; at the moment, the grounding point of the branch k, namely, the space between the branch switch k and the branch direct current transformer k is isolated from a direct current system, and the non-grounding part is continuously supplied with power by a direct current bus through a bypass; the system sends out a direct current fault isolation and bypass starting alarm message;
step six: according to a preset program of the system, namely according to preset numbers of branches 1 to n, firstly closing a bypass switch, then closing the bypass switch 1 according to the numbers, disconnecting the bypass switch 1, and the like, immediately stopping switching until the voltage is recovered to be normal, and judging that a branch k (k is less than or equal to n) switched for the last time has a grounding point; simultaneously, starting the direct current shunt from k-1, which is already switched, firstly closing the corresponding shunt switch k-1, separating the corresponding side shunt switch k-1, closing the corresponding shunt switch k-2, separating the corresponding side shunt switch k-2, and the like, switching, and recovering the original operation mode; at the moment, the grounding point of the shunt k, namely, the shunt switch k and the shunt direct current transformer k are isolated from the direct current system, the non-grounding part is continuously supplied with power through the bypass by the direct current bus, and the system sends out direct current fault isolation and bypass starting alarm information.
In summary, the real-time monitoring system for the ground fault of the direct current system and the control method thereof can rapidly locate the zone where the ground point is located through the differential protection device, and only the line in the zone needs to be searched, so that the searching time is greatly shortened, and the rapid location of the ground fault point is realized. The invention discloses a real-time monitoring system for the ground fault of a direct current system and a control method thereof, wherein the real-time monitoring system controls a motor to complete automatic switching on and switching off of a switch, automatically completes a searching link of the ground fault of the direct current system, automatically isolates the fault after finding out a fault point, and adopts a bypass to recover power transmission; the fault can be rapidly located and found, and the fault can be automatically isolated. The real-time monitoring system for the ground fault of the direct current system and the control method thereof provide a bypass loop, and the bypass is adopted to recover power transmission, so that the power supply requirement of the load carried by a fault line is recovered, and a standby power supply is not required to be increased.
Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. The direct current system ground fault real-time monitoring system is characterized by comprising a voltage detection device, a direct current transformer, a differential protection device, a switch deflection acquisition module, an opening module, a DSP module, a CPU controller, a memory, an opening module, a communication module, a display device, a motor control module, a main switch, a branch switch, a shunt switch, a bypass switch and a bypass switch, wherein the main switch is used for controlling opening and closing by a motor;
the output end of the voltage detection device is connected with the input end of the opening module, the voltage detection device transmits signals acquired in real time to the opening module, and the voltage detection device is used for detecting the voltage of the direct current bus in real time;
the output end of the direct current transformer is connected with the input end of the opening-in module, the direct current transformer transmits signals acquired in real time to the opening-in module, and the direct current transformer is used for acquiring currents flowing through the main switches, the branch switches and the shunt switches in real time;
the input end of the differential protection device is connected with the output end of the direct current transformer, the output end of the differential protection device is connected with the input end of the CPU controller, the differential protection device is used for monitoring differential current in the protection range in real time, and when detecting that the differential current is greater than the action fixed value of the differential protection device, the differential protection device sends an abnormal instruction to the CPU controller;
the output end of the switch deflection acquisition module is connected with the input end of the switch-in module, the switch deflection acquisition module changes a switch acquired in real time into a signal and transmits the signal to the switch-in module, and the switch deflection acquisition module is used for monitoring the switch to become information;
the input end of the switch deflection acquisition module is connected with the input end of the DSP module, and the switch deflection acquisition module is used for acquiring signals acquired by the voltage detection device, the direct current transformer and the switch deflection acquisition module in real time and transmitting the signals to the CPU controller through the DSP module;
the output end of the DSP module is connected with the input end of the CPU controller; the DSP module is used for converting the analog signals of the starting module into digital signals and transmitting the digital signals to the CPU controller;
the output end of the CPU controller is connected with the input end of the memory, and the CPU controller judges that the direct current system is in a normal or abnormal state currently through monitoring and analyzing signals, marks abnormal data and stores the abnormal data in the memory;
the input end of the opening module is connected with the output end of the CPU controller, and the output end of the opening module is connected with the input end of the communication module; the opening module is used for executing the command sent by the CPU controller and transmitting the command through the communication module;
the output end of the communication module is respectively connected with the input ends of the display device and the motor control module, and the communication module is used for receiving the signal transmitted by the opening module and displaying the alarm information on the display device;
the output end of the motor control module is respectively connected with the control ends of the main switch, the branch switch, the shunt switch, the bypass switch and the bypass switch, the motor control module receives the command transmitted by the communication module, and the motor control module realizes the switching of all the switches by controlling the forward and reverse rotation of the motor.
2. The direct current system ground fault real-time monitoring system according to claim 1, wherein the direct current bus is connected with a plurality of total switches, each total switch is connected with a plurality of branch switches, and each branch switch is connected with a plurality of branch switches; each branch switch is connected to the bypass switch through a bypass switch, and each branch switch is connected to the bypass switch through a bypass separator, and the bypass switch is connected with the direct current bus.
3. The system of claim 1, wherein the differential protection device has an action constant value of 20% or more of differential current, i.e. I differential is equal to or greater than 20%, and differential current percentage = absolute value of vector sum of all branch currents/absolute value of total branch current is 100%.
4. The direct current system ground fault real-time monitoring system according to claim 1, further comprising a background control center and an intelligent mobile terminal, wherein the input end of the background control center is connected with the output end of the communication module, and the output end of the background control center is connected with the intelligent mobile terminal; the communication module transmits the signals to the background control center in a remote mode, and the background control center transmits the signals to the intelligent mobile terminal through wireless communication.
5. A control method of a direct current system ground fault real-time monitoring system according to claim 1, comprising the steps of:
step one: when the voltage abrupt change U1 collected by the voltage monitoring device is less than 20 percent and the differential current I differential of the differential protection device is less than 20 percent, the voltage and the current are both normal interval values, the system control display device displays the normal running state of the system, and the system enters a normal running program;
step two: when the voltage abrupt change U1 collected by the voltage monitoring device is more than or equal to 20 percent and the differential current I differential of the differential protection device is less than 20 percent, the system detects that the voltage is obviously reduced, the system judges that the direct-current voltage is abnormal, the system controls the display device to send a direct-current voltage abnormality alarm, and the alarm information is uploaded to the background control center, so that the system enters a direct-current voltage abnormal operation program;
step three: when the voltage abrupt change U1 collected by the voltage monitoring device is less than 20 percent and the differential current I differential of the differential protection device is more than or equal to 20 percent, the system judges that the direct current is abnormal, the system controls the display device to send out a direct current abnormal alarm, and the alarm information is uploaded to the background control center, so that the system enters a direct current abnormal operation program;
step four: when the voltage abrupt change U1 collected by the voltage monitoring device is more than or equal to 20 percent and the differential current I differential of the differential protection device is more than or equal to 20 percent, the system judges that direct current grounding exists, the system controls the display device to send out a direct current grounding alarm, and the alarm information is uploaded to the background control center, so that the system enters a direct current grounding operation program; the system locates the protection range of the corresponding differential protection device and starts to search the fault line in the protection range; if the protection range of the system positioning differential protection device is a branch, executing a step five; if the protection range of the system positioning differential protection device is a shunt, executing the step six;
step five: according to a preset program of the system, namely according to preset numbers of branches 1 to n, firstly closing a bypass switch, then closing the bypass switch 1 according to the numbers, disconnecting the bypass switch 1, and the like, immediately stopping switching until the voltage is recovered to be normal, and judging that a grounding point exists in a branch k (k is less than or equal to n) switched for the last time; simultaneously, starting from k-1, switching the direct current branch which is already switched, firstly closing the corresponding branch switch k-1, separating the corresponding branch switch k-1, closing the corresponding branch switch k-2, separating the corresponding branch switch k-2, and the like, switching and recovering the original operation mode; at the moment, the grounding point of the branch k, namely, the space between the branch switch k and the branch direct current transformer k is isolated from a direct current system, and the non-grounding part is continuously supplied with power by a direct current bus through a bypass; the system sends out a direct current fault isolation and bypass starting alarm message;
step six: according to a preset program of the system, namely according to preset numbers of branches 1 to n, firstly closing a bypass switch, then closing the bypass switch 1 according to the numbers, disconnecting the bypass switch 1, and the like, immediately stopping switching until the voltage is recovered to be normal, and judging that a branch k (k is less than or equal to n) switched for the last time has a grounding point; simultaneously, starting the direct current shunt from k-1, which is already switched, firstly closing the corresponding shunt switch k-1, separating the corresponding side shunt switch k-1, closing the corresponding shunt switch k-2, separating the corresponding side shunt switch k-2, and the like, switching, and recovering the original operation mode; at the moment, the grounding point of the shunt k, namely, the shunt switch k and the shunt direct current transformer k are isolated from the direct current system, the non-grounding part is continuously supplied with power through the bypass by the direct current bus, and the system sends out direct current fault isolation and bypass starting alarm information.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311538692.0A CN117491905A (en) | 2023-11-17 | 2023-11-17 | DC system ground fault real-time monitoring system and control method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311538692.0A CN117491905A (en) | 2023-11-17 | 2023-11-17 | DC system ground fault real-time monitoring system and control method thereof |
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